Big fan of tusker (https://github.com/bikeshedder/tusker) for PostgreSQL migrations. Tusker takes a SQL-first approach; You write your schema in declarative DDL (I have my entire project in one schema.sql file) and when you edit it, tusker generates the sql code required to migrate. It uses temporary test databases to run both your declarative DDL and your step-by-step migrations to ensure they are in lock step. And it can connect to live databases and diff your schema/migrations against reality. I've never seen a better toolkit for schema evolution.